Package lifting system and method

Abstract

The invention relates to a lifting system (1) for a package (C), preferably in the presence of waves, comprising: - at least one lifting cable (3) associated with a winch (4), pulley means (5) including a fixed block of sheaves (51) and a movable block of sheaves (52), - controlled braking means (6), cooperating with said movable block of sheaves and controllable between an inactive configuration in which said controlled braking means allow free translation of said movable block of sheaves, and an active configuration in which said controlled braking means allow movement of the movable block of sheaves only in one direction, - control means (7) for controlling said winch and the controlled braking means, and - operating means (8) configured to restore potential energy to said movable block of sheaves. Figure for the abstract: Fig. 1

Description

Title of the invention: System and method for lifting packages Technical field of the invention

[0001] The present invention relates to the technical field of parcel lifting.

[0002] It relates more particularly to a system and a method for lifting packages in the presence of a relative movement between the lifting system and the area where the package is located or is to be deposited, due for example to swell. State of the art

[0003] It is common to use package lifting systems at sea, in particular for loading or unloading ships, barges or offshore platforms.

[0004] In this context, a lifting device such as a crane or a gantry is usually used, equipped with at least one cable, one end of which is adapted to wind onto a winch and the other end of which carries the package.

[0005] In the specific field of sea lifting, the main difficulty encountered concerns the relative speeds between the reference frame of the lifting equipment and the reference frame on which the package is placed or is to be placed.

[0006] Traditionally, the winches of offshore lifting systems have high lifting speeds so as to allow experienced crane operators to follow the movements of the swell by actions known as tacking and turning.

[0007] The lifting of the package from the bridge is done initially by always leaving slack in the lifting straps, then by taking up the slack on a phase of lifting the package in order to accompany the natural movement of the package imposed by the swell.

[0008] To assist crane operators, there are now cranes with active wave compensation that automatically compensate for relative movements between the two reference frames.

[0009] This active compensation aims to keep the cables taut at all times so as to avoid a shock of slack resumption.

[0010] However, in practice, this technical solution is cumbersome, expensive and very dependent on sensors.

[0011] Another solution consists of shock-absorbing cranes: a shock-absorbing device, generally hydraulic, filters out as dynamically as possible any force exceeding a certain preset threshold.

[0012] However, this type of solution is not able to recover from significant shocks due to very high relative speeds.

[0013] In view of the above, it would be interesting to propose alternative solutions adapted to lifting packages in the presence of relative movement due to the swell.

[0014] In particular, it would be interesting to propose a mechanical solution which aims not only to treat the effects of shocks but to make them impossible, or at least to limit them. Presentation of the invention

[0015] In this context, the present invention proposes a system for lifting a package, preferably between two reference frames exhibiting at least one relative vertical movement, for example for lifting the package in the presence of relative movement due to swell, which lifting system comprises at least one lifting point which includes a frame comprising: - at least one lifting cable associated with: H a winch, for maneuvering said lifting cable, in turns and in turns, H means of pulley systems including: ° a fixed block of sheaves, attached to said chassis, and ° a movable block of sheaves, cooperating with said frame by means of sliding means defining a degree of freedom in translation orthogonally to the axes of rotation of said sheave blocks, the dimension in distance of said movable block of sheaves relative to said fixed block of sheaves being variable, - controlled braking means, cooperating with said mobile block of sheaves and controllable between two preferably bistable configurations: H an inactive configuration, in which said controlled braking means allow free translation of said moving block of sheave(s) according to said degree of freedom in translation, particularly adapted to passive wave compensation, and H an active configuration, in which said controlled braking means allow the moving block of sheaves to move in a single direction according to said degree of freedom in translation, corresponding to an increase in said dimension in distance, - control means, for piloting said winch and said controlled braking means, in particular during launching or retrieval operations of said package, - the first means of operation which cooperate with said mobile block of sheaves and which are configured to restore potential energy to said mobile block of sheaves such as: H when said controlled braking means are in inactive configuration, to tend to maintain a constant tension in said at least one lifting cable and, H when the said controlled braking means are in active configuration, tending to increase said rating in distance.

[0016] According to the invention, said sliding means comprise a sliding rod which carries the movable block of sheaves, which is guided in translation coaxially to said translational degree of freedom and which cooperates with said controlled braking means, while said controlled braking means comprise: - at least two jaws distributed around said sliding rod, each of which jaws has a friction face adapted to cooperate with said sliding rod, and - second bistable means of operation adapted to move each jaw between two positions: H a distal position, at a distance from said sliding rod, corresponding to said inactive configuration of said controlled braking means, and H a proximal position, supported on said sliding rod, corresponding to said active configuration of the controlled braking means.

[0017] Consequently, the controlled braking means are adapted, in their inactive configuration, to allow the pulley system to take up or give slack in the lifting cable. This configuration is particularly useful when the package must remain resting on a reference frame that is moving relative to the one on which the lifting system is located. Furthermore, in their active configuration, these controlled braking means are adapted to allow the pulley system to take up slack in the lifting cable but to prevent it from giving slack. This configuration is particularly useful when the package must be lifted from the moving reference frame.

[0018] The solution proposed by the invention, using jaws, then proves to be particularly interesting in several respects.

[0019] First, it relies essentially, if not exclusively, on mechanical means (advantageously limiting the number of sensors and actions of an automated system in real time), which makes it particularly robust and reliable, even in the harsh environmental conditions of marine and offshore environments. Indeed, it is possible to designate that only the winch and bistable maneuvering means are controlled. It would even be possible to envision the bistable maneuvering means taking the form of a simple lever.

[0020] This solution also allows packages to be lifted and placed down in the gentlest possible way, regardless of the relative speeds of the reference frames, even when the latter exceed the recommendations (typically if a particularly high and unpredictable wave occurs).

[0021] Finally, it is inexpensive, lightweight and compact.

[0022] Other advantageous and non-limiting features of the lifting system according to the invention, taken individually or in all technically possible combinations, are as follows: - the friction faces of the jaws extend parallel to said degree of freedom in translation; - said second means of maneuvering guide the movement of each jaw along an arc-shaped trajectory in which said friction face moves parallel to itself, between said two distal and proximal positions; - the second means of operation include an actuator and, for each jaw, a deformable parallelogram structure which includes said jaw, a base, and at least two connecting rods each assembled in free rotation with said base and with said jaw around two distinct pivot axes, which deformable parallelogram structure cooperates with said actuator for the maneuvering of said jaw between its distal position and its proximal position; - at least two connecting rods, belonging to two distinct deformable parallelogram structures, cooperate together by means of gears, so as to ensure the synchronization of the associated jaws; - in proximal position, the angle between the plane passing through the pivot axes of each connecting rod and the normal to the friction face is between 6 and 9° if the coefficient of adhesion friction between each friction face and said sliding rod is between 0.08 and 0.16; - at the level of each jaw, given a resultant angle, corresponding to an angle formed by the resultant of the forces applied between said jaw and said sliding rod, and an angle at the apex of a friction cone, corresponding to the maximum angle with respect to a contact normal oriented perpendicularly to said sliding rod in which a force can be applied to the sliding rod according to said degree of freedom in translation without generating translation of said sliding rod, said lifting system is configured so that, when the jaws are in active configuration, said resultant angle is less than said angle at the apex of the friction cone; - the controlled braking means include mechanical stops to define an end-of-stroke position for the jaws which is located beyond said proximal position and which is such that, in the end-of-stroke position, all the components of the controlled braking means are deformed elastically only; - the sliding means are configured so that said sliding rod, and its degree of freedom in translation, are oriented horizontally; - the sliding means are configured so that said sliding rod, and its degree of freedom in translation, are oriented vertically; - when said degree of freedom in translation is oriented horizontally, said sliding rod is supported by support rollers; - when said translational degree of freedom is oriented vertically, the controlled braking means include means for compensating the weight of the jaws, by for example a spring or a counterweight; - the first means of operation, configured to restore elastic potential energy or gravitational potential energy on said moving block of sheave(s), include an elastically deformable element such as a spring or an elastic band, and / or a counterweight; - the controlled braking means include safety means which are configured to prevent a steering from the inactive configuration to the active configuration during a translation of the sliding rod corresponding to a decrease in said dimension in distance; - the safety means include a safety ring which encircles said sliding rod so as to move between two positions, namely an active position, during a translation of the sliding rod corresponding to a decrease in said dimension in distance, to cooperate with the jaws in the inactive configuration and prevent piloting from the inactive configuration to the active configuration, and an inactive position, during a translation of the sliding rod corresponding to an increase in said dimension in distance, to move away from the jaws in the inactive configuration and to allow piloting from said inactive configuration to said active configuration; - the lifting system consists of a crane having one lifting point, the chassis of which has a stile and a boom, or of a gantry having at least two lifting points.

[0023] The invention also proposes a method for lifting a package between two reference frames preferably exhibiting at least one relative vertical motion, for example, for lifting the package in the presence of relative motion due to swell, by implementing a lifting system as described above, which lifting method comprising - for moving the jaws from the proximal to the distal position: H the control of the second means of maneuver to move the jaws from the proximal to the distal position, then, H if a force exerted on the sliding rod coaxially with said degree of freedom in translation in a direction corresponding to a decrease in said dimension in distance is less than a predetermined threshold, execution of said command, otherwise H suspends said order until said effort decreases below said predetermined threshold, then executes said order, - for the transition from the distal to the proximal position of the bits: H the control of the second means of maneuver to move the jaws from the distal position to the proximal position, then, If the said distance dimension increases, the said command is executed; otherwise, the said command is suspended until the said distance dimension increases. increase.

[0024] Preferably, this lifting method comprises the following operations: (i) during an operation to launch said package from the lifting system's reference point to a destination reference point: - a stage of suspending said package from said lifting cable, in which the jaws are in a distal position and said mobile block of sheaves is in a mid-position centered on an available stroke, - a turning and drifting stage over a course allowing the safety ring to be positioned in the inactive position, - a step to control the closing of the jaws towards the proximal position, - a turning step to lift the package and place it above the destination repository, - a stage of lowering said package near the highest wave crests of the swell, - when the package is placed on a wave crest or near a wave crest at the end of a rising front, a deflection step, preferably to come tangent to said wave crest, and a transition from the proximal to the distal position of the jaws, so that when said package transfers its weight from said lifting cable to said destination reference frame, said lifting system provides passive compensation for the swell, and / or (ii) during a retrieval operation of said package located on the destination datum, with the jaws in the distal position, said lifting system providing passive compensation for swell, - preferably when said package is in an upward movement, a step of passing the jaws into a proximal position so that said mobile block of sheaves continues its movement increasing said dimension in distance, up to a wave crest where said mobile block of sheaves is blocked in translation, - as soon as the jaws reach the proximal position, a turning step to lift the package and place it above the lifting system's reference point, - a step of lowering said package onto the lifting system's reference point.

[0025] Of course, the various features, variants, and embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. Detailed description of the invention

[0026] The following description, with reference to the accompanying drawings, given by way of non-limiting examples, will clearly explain what the invention consists of and how it can to be carried out.

[0027] On the attached drawings:

[0028] [Fig-1] is a general schematic and perspective view of a lifting system according to the invention, according to a first embodiment (vertical), in the form of a crane comprising a lifting point;

[0029] [Fig.2] is a schematic and perspective view of the lifting system according to [Fig.1], on which the chassis is masked and which illustrates in particular means of reeving and braking of this lifting system;

[0030] [Fig.3] is a schematic and perspective view of controlled braking means which cooperate with the pulley means of [Fig.2], seen in a first direction;

[0031] [Fig.4] is a schematic plan view of the controlled braking means of [Fig.3], seen from a second direction opposite to [Fig.3];

[0032] [Fig.5] is a schematic and perspective view of a safety ring equipping the controlled braking means of the [Fig.3];

[0033] [Fig.6] illustrates different configurations that can be taken by the controlled braking means of [Fig.3];

[0034] [Fig.7] is a schematic and perspective view of the lifting system according to a second embodiment (horizontal);

[0035] [Fig.8] is a cross-sectional view along plane AA of [Fig.7].

[0036] Lifting system

[0037] It should be noted that, in these figures, the structural and / or functional elements common to the different variants may have the same references.

[0038] As shown in [Fig.1], the present invention relates to a lifting system 1 designed for lifting a package C.

[0039] This lifting system 1 is particularly suitable for lifting a package C in the presence of relative movement due to swell, in particular for an offshore or sea application.

[0040] More generally, the lifting system 1, for example a crane or a gantry, is adapted to the handling of a package C between two reference frames which have a relative movement due to the swell.

[0041] By "swell" is meant the oscillation of the sea surface, in particular due to waves.

[0042] Generally, the highest point of a wave is called the crest; the lowest point is called the trough. The size of the wave is determined by the distance between the crest and the trough. The period is the time elapsed between two crests.

[0043] As mentioned later, a "highest peak" advantageously corresponds to the highest peak during a given period of time.

[0044] The term "package" includes any object (or load) intended to be handled by the Lifting system 1. Such a package C can have various shapes and sizes. It can, for example, be a platform for transferring people ([Fig.1] for example), a container or a boat.

[0045] The term "reference frames" advantageously encompasses any surface which, for one of them, supports the lifting system 1 and, for the other of them, is intended to receive the package C. In the following, we will refer respectively to the origin reference frame Ro and the destination reference frame Rd. This could be, for example, the deck of a ship or a platform, or even the surface of the water.

[0046] Generally, and according to the invention, the lifting system 1 comprises at least one lifting point la, that is to say, a system by which it can lift a package independently. Alternatively, the lifting system 1 may comprise at least two lifting points la, for lifting several separate packages or for lifting the same package from several points.

[0047] According to the invention, this lifting point comprises a chassis 2 equipped with: - at least one lifting cable 3 associated with a winch 4 and pulley systems 5, - controlled braking means 6, cooperating with the pulley systems 5, - the first 8 maneuvering means which cooperate with the 5 pulley systems and which are configured to restore potential energy, in particular to keep the pulley systems taut and ensure passive swell compensation, and - control means 7, for piloting the winch 4 and possibly also pilot-controlled braking means 6, particularly during launching or retrieval operations of package C.

[0048] Lifting cable

[0049] The lifting cable 3 is conventional in itself.

[0050] It consists, for example, of a cable made of synthetic material or metallic material.

[0051] This lifting cable 3 is capable of withstanding a tensile force which is generated by the package C suspended from said lifting cable 3.

[0052] In other words, package C is intended to be suspended from one end of the lifting cable 3 when the other end is wound around the winch 4. When suspended, this package C is thus intended to exert a pulling effort, or a pulling force, on the lifting cable 3.

[0053] By “suspended” we mean a configuration in which the package C is located at a height and distance from the reference points.

[0054] Winch

[0055] Winch 4 is classic in itself.

[0056] This winch 4 is adapted for operating the lifting cable 3: - in turn, to exert force on the lifting cable 3 by winding it onto a drum of the winch 4, and advantageously to generate an upward movement of the package C from the destination reference point, and - deviates, to release the effort on the lifting cable 3 by unwinding from the winch 4, and advantageously to generate a descent of the package C towards the destination reference point.

[0057] Means of pulley

[0058] The pulley means 5, more clearly visible in [Fig.2], include: - a fixed block of sheaves 51, attached to chassis 2, and - a mobile block of sheaves 52, mounted movably in translation on the frame 2 by means of slides 53 defining a degree of freedom in translation T.

[0059] In particular, the mobile block of sheaves 52 preferably comprises a single sheave 52 or two sheaves 52.

[0060] Preferably, the sheaves 51, 52 (also called "pulleys") have respective axes of rotation 51', 52', which extend in planes orthogonal to the degree of freedom in translation T (also called "axis of the slide"), which are parallel to each other and which define between them a dimension in distance D.

[0061] The dimension in distance D is advantageously measured according to the degree of freedom in translation T, described below.

[0062] The slide means 53 define a translational degree of freedom for the moving block of sheaves 52. This is preferably the only degree of freedom between the two blocks of sheaves.

[0063] This translational degree of freedom T extends along an axis, hereinafter also called "Slider axis T", which can be oriented vertically (figures 1 to 6) or horizontally (figures 7 and 8). Of course, this slider axis T could extend obliquely.

[0064] As further developed, the aforementioned distance dimension D (corresponding to the distance between the rotation axis 52' of the moving block of sheaves 52 and the rotation axis 51' of the fixed block of sheaves 51, measured on the translational degree of freedom) is variable.

[0065] For example, the possible stroke of the mobile block of sheave(s) 52, according to the degree of freedom in translation, is for example from 1 m to 2 m, for example from 1.5 m (i.e. from 6 m to the hook).

[0066] Generally, the means slides 53 include, for example, a sliding spar 531 (also called a "sliding rod"), forming a slide, which carries the mobile block of sheaves 52.

[0067] Where applicable, the sliding spar 531 extends coaxially to the slide axis T. This sliding spar 531 is movable along this slide axis T.

[0068] The mobile block of sheaves 52 is advantageously mounted at the level of one of the ex- openings 531a, 531b of the sliding spar 531.

[0069] As developed below, this sliding spar 531 cooperates with the controlled braking means 6. The latter thus make it possible to brake or block the sliding of the sliding spar 531 and the mobile block of sheaves 52. Here, they also make it possible to guide this sliding spar 531, in translation, along the slide axis T.

[0070] Controlled braking means

[0071] According to the invention, the controlled braking means 6 are controllable between two configurations, advantageously bistable: an inactive configuration and an active configuration.

[0072] By "bistable," it is advantageously understood that the inactive and active configurations constitute stable configurations. Preferably, these controlled braking means 6 cannot be controlled in any other configuration; the controlled braking means 6 thus advantageously switch between the inactive and active configurations. They may, however, optionally exhibit a different configuration, particularly during the transition from one to the other of the two stable configurations.

[0073] In the inactive configuration, the controlled braking means 6 allow free translation of the mobile block of sheaves 52 along the slide axis T, in both directions (for example along an oscillating movement).

[0074] As further developed, such an inactive configuration is particularly well-suited to passive wave compensation. In this case, the movable block of sheaves 52 and the sliding spar 531 can oscillate freely relative to the fixed block of sheaves 51, notably as a function of the relative motion between the two reference frames. This is typically the case when the package C is placed on the destination reference frame Rd and the two reference frames Ro, Rd rise and fall relative to each other due to the waves.

[0075] In the active configuration, the controlled braking means 6 allow movement of the sheave block(s) 52 in only one direction along the slide axis T, corresponding to an increase in the aforementioned distance dimension D. In other words, in the active configuration, the pulley means 5 can take up the slack in the lifting cable 3, but they remain locked when a tensile force is applied to this lifting cable 3 (when the package C is suspended from the end of this lifting cable 3). For example, in Figures 1 and 2, only downward movement of the sheave block(s) 52 is permitted, to ensure the lifting of the package C, its descent being blocked. This is typically the case when the package C was placed on the destination reference frame Rd and it is desired to lift it, or when the package C is rising relative to the lifting system 1.

[0076] In other words, in the active configuration, the controlled braking means 6 are structured for: - allow the mobile block of sheaves 52 to move in a first direction along the axis of the slide T, corresponding to an increase in the dimension in distance D, and - prevent the mobile block of sheaves 52 from moving in a second direction along the axis of the slide T, corresponding to a decrease in the dimension in distance D.

[0077] Such an active configuration is particularly interesting for allowing the continuation of a movement increasing in the distance D, for example when the package C follows an upward trajectory up to a wave crest, and for preventing it from then falling back down towards the trough of the wave since we want to lift it.

[0078] Mors

[0079] According to the invention, the controlled braking means 6 essentially comprise mechanical means, mounted movably relative to each other to define the aforementioned active and inactive configurations.

[0080] More specifically, according to an example illustrated in [Fig.3], the controlled braking means 6 first of all include a base 61, in this case a housing 61, which is fixed to the chassis 2 and which houses jaws 631, 632.

[0081] These jaws 631, 632 are preferably located on either side of the sliding rod 531 so as to be able to sandwich it. Preferably, these jaws 631, 632 are for this purpose mounted to move in a direction inclined with respect to the axis of the slide T in order to bear against this sliding rod 531 or to move away from it, depending on the direction of travel.

[0082] The jaws 631, 632 further each have a friction face 631a, 632a, these faces being turned towards each other and towards the sliding rod 531. These friction faces 631a, 632a are intended to cooperate with the sliding rod 531 to ensure its braking.

[0083] The sliding rod 531 is said to be profiled, in that it has, over at least part of its length (that which slides in the housing 61), a section of invariable shape and size.

[0084] The friction faces 631a, 632a of the jaws 631, 632 have complementary shapes, in negative, to those of the parts of the sliding rod 531 against which they rest.

[0085] Here, and preferably, the sliding rod 531 has a circular cross-section. Consequently, the friction faces 631a, 632a of the jaws 631, 632 are curved, in that they have cross-sections (in planes orthogonal to the slide axis T) in the form of arcs of a circle, extending over angular sectors less than or equal to 180°.

[0086] Of course, alternatively, the sliding rod 531 could have a rec section tangential, in which case the friction faces 631a, 632a of the jaws 631, 632 would be planar or dihedral. Other shapes would also be conceivable.

[0087] In practice, the jaws 631, 632 are advantageously presented in the form of parallelepiped blocks, one of whose six faces forms the friction face 631a, 632a.

[0088] The jaws 631, 632 could be made from a wide variety of materials. Here, they are formed from a single piece of a single metallic material, for example, mild stainless steel (whereas the sliding rod 531 is made of hard stainless steel). Of course, alternatively, it would be possible to make them from another material or from several different materials (for example, to coat their friction faces 631a, 632a with a special material designed to brake the sliding rod 531).

[0089] The controlled braking means 6 also include second bistable operating means 60 adapted to move the jaws 631, 632 so that the latter can move closer to or further away from the sliding rod 531.

[0090] These bistable maneuvering means 60 are configured to allow the jaws 631, 632 to be moved between two positions, namely: - a distal position in which the jaws 631, 632 extend at a distance from the sliding rod 531, and - a proximal position in which the jaws 631, 632 come to rest on said sliding rod 531.

[0091] By "at a distance" we mean that the jaws 631, 632 are in a position offset from the sliding rod 531 relative to the proximal position, and such that they do not prevent the sliding rod 531 from sliding according to its degree of freedom in translation, in both directions. In practice, in this position, it is preferable that no contact occur between the jaws 631, 632 and the sliding rod 531. However, alternatively, a partial sliding support could be envisaged, similar to the brake discs of motor vehicles.

[0092] When the jaws 631, 632 are in the distal position (advantageously separated from the sliding rod 531), they do not therefore block the sliding of the sliding rod 531 according to its translational degree of freedom. Consequently, this distal position corresponds to the inactive configuration of said controlled braking means 6.

[0093] When the jaws 631, 632 are in the proximal position (advantageously bearing on the sliding rod 531), they block the sliding of the sliding rod 531 along the slide axis T in only one direction, for the reason that will be described below. Consequently, this proximal position corresponds to the active configuration of the pilot-operated braking means 6.

[0094] Various systems could be considered so that, when the jaws are in the proximal position, they block the sliding of the sliding rod 531 in only one direction.

[0095] Here, the second means of maneuver 60 are in practice shaped to guide the movement of the jaws 631, 632 along arc-shaped trajectories, so that the friction faces 631a, 632a move parallel to each other, between the two distal and proximal positions.

[0096] They are more precisely arranged so that, when the jaws 631, 632 move from the distal position to the proximal position, these jaws 631, 632 move along the slide axis T, in a direction corresponding to a reduction in the dimension in distance D.

[0097] These second means of operation 60 are further shaped so that the arc-shaped trajectories of the friction faces 631a, 632a of the jaws 631, 632 are not tangent to the sliding rod 531. Thus, in the proximal position (when the jaws rest against the sliding rod 531), the movement of the sliding rod 531 in one direction (that corresponding to a reduction in the dimension in distance D) will tend, given the friction of the jaws 631, 632 on this sliding rod 531, to tighten the jaws 631, 632 against the sliding rod 531. Conversely, the movement of the sliding rod 531 in the opposite direction will tend to move the jaws 631, 632 away from this sliding rod 531. It is this aspect that makes it possible here to prevent the movement of the sliding rod 531 in one direction only.

[0098] In practice, this so-called "rotary translation" movement of the jaws 631, 632 is operated by two deformable parallelogram structures.

[0099] For each jaw 631, 632, the deformable parallelogram structure comprises:

[0100] - said jaw 631, 632,

[0101] - base 61, and

[0102] - at least two connecting rods 602, 603, 604, 605, each assembled for free rotation with said base 61 and with said jaw 631, 632 around two distinct pivot axes.

[0103] As shown in [Fig. 3], these structures each comprise, for example, two connecting rods 602, 604; 603, 605 which are articulated, here at their ends, on the one hand to the housing 61, and on the other hand to the jaw 631; 632 under consideration. In other words, each jaw 631, 632 cooperates with a pair of connecting rods 602, 604; 603, 605.

[0104] For this purpose, the housing includes a bottom wall 610 from which rise four first cylindrical pads 612, 613, 614, 615 of revolution around axes parallel and orthogonal to the slide axis T.

[0105] Each connecting rod 602, 603, 604, 605 has a plate shape with openings at both ends, one of which is engaged with one of the first pads 612, 613, 614, 615. The first pads 612, 613, 614, 615 thus ensure the guidance of each associated connecting rod 602, 603, 604, 605 through pivoting movements around respective pivot axes corresponding to the axes cones.

[0106] Similarly, each jaw 631, 632 carries two second pads, not visible on the [Fig.3], cylindrical of revolution around axes parallel to the axes of the first pads 612, 613, 614, 615. The second opening of each connecting rod 602, 603, 604, 605 is then engaged on one of these second pads.

[0107] Generally, the first and second studs are positioned such that the two connecting rods 602, 604; 603, 605 (thus articulated on each jaw 631; 632) are elongated along parallel axes. The longitudinal axis of a connecting rod will be defined here as the axis that passes through the mid-thickness of the connecting rod and intersects the axes of the first and second studs on which this connecting rod is articulated.

[0108] Each deformable parallelogram structure thus comprises: - a fixed side, formed by the housing and two of its first supports, - two movable sides rotating around the axes of these first supports, formed by the connecting rods, and - a movable side in rotational translation formed by the jaw.

[0109] It is necessary that the two deformable parallelogram structures act in concert on the sliding rod 531, that is to say that the jaws exert symmetrical stresses on this sliding rod 531.

[0110] For this purpose, the movements of the two jaws 631, 632 are symmetrical and synchronized, here by means of gears 602a, 603a, 604a, 605a.

[0111] Various gear systems could be used for this purpose. In the example illustrated in [Fig.4], the solution consists of forming teeth adapted to mesh on the ends of the connecting rods 602, 603, 604, 605.

[0112] The two connecting rods 602, 604 of one of the jaws then have several teeth which mesh respectively with teeth of the two connecting rods 603, 605 of the other jaw. In this way, when a movement is imparted to one of the jaws 631, 632, this movement is mechanically transmitted to the other jaw.

[0113] Alternatively, other transmission means could have been used for the same purpose. Typically, it would be possible to use a connecting rod that would force the two jaws to move up or down in unison (along the axis of the slide T).

[0114] Actuator

[0115] To move the jaws 631, 632 between their distal and proximal positions, the second means of operation 60 advantageously include an actuator 601a, advantageously a bistable actuator, preferably associated with a timing element 601b, for example a spring box 601b.

[0116] The actuator 601a could include a manual operating lever.

[0117] Here, it is more a question of a controlled actuator.

[0118] This piloted actuator 601a preferably comprises a cylinder. It may be a electric or pneumatic cylinder, or even hydraulic.

[0119] In any case, it is a double-acting cylinder, allowing the jaws 631,632 to be moved:

[0120] - from the distal position to the proximal position, and

[0121] - from the proximal position to the distal position.

[0122] In practice, this jack comprises a cylinder which is mounted on a frame.

[0123] Furthermore, the spring box 601b is in practice articulated on the housing 61 via a ball joint type connection.

[0124] The 601b spring box has a free end which is coupled:

[0125] - to one of the jaws or

[0126] - to one of the connecting rods housed in this housing 61.

[0127] This free end is here articulated on one of the connecting rods 605 via a ball joint type connection.

[0128] Thus, the second means of maneuver 60 are attached to only one of the deformable parallelogram structures, the other being actuated by the aforementioned gear system.

[0129] In general and advantageously, the bistable actuator 601a translates the operator's instructions (package in lifting mode or package in passive wave compensation mode), which is "stored" by the timing element 601b.

[0130] The execution, corresponding to the actual movement of the jaws, is conditioned by the safety conditions of the lifting operation:

[0131] - the controlled braking means 6 do not put the package into free fall even if the operator wants to switch to passive compensation; the controlled braking means 6 wait until the self-weight has been taken up by the destination reference frame so that the jaws open at that precise moment, pushed "passively" by the timing device which has been pre-stressed by the change in position of the control;

[0132] - the controlled braking means 6 do not instantaneously block the movement of lowering of the package even if the operator requests it; the jaws close, but on the safety ring which remains between the jaws until arrival at the lowest point; once the package begins to rise, the safety ring is driven out of the jaws and they rest on the sliding rod which is not blocked in the direction of the upward movement of the package; when the package reaches its apogee and it wants to begin to descend, the jaws block the movement of the sliding rod and thus the package rests at theoretical zero speed on the lifting cable(s).

[0133] In other words, and advantageously, the controlled braking means 6 do not execute the operator's commands in real time but wait for opportune moments (those that ensure the safety of the operation) to do so. This is done passively, purely mechanically, that is to say, without the need for management of Real-time sensors and actuators are controlled by the PLC or the operator. This approach makes it a solution where useful actions are naturally performed at the right times, and therefore in an inherently safe and reliable manner.

[0134] Adhesion friction cone

[0135] At this stage, we can define more precisely how the second means of operation 60 are designed in order to ensure that, in the proximal position, the jaws 631, 632 can block the sliding rod 531 if the latter tends to slide in one direction and that they allow it to slide if it tends to slide in the opposite direction.

[0136] For this, it is necessary to define a "resultant angle" for each jaw.

[0137] This angle corresponds to the angle formed by the resultant of the forces applied by the jaw 631, 632 considered on the sliding rod 531. This resultant is composed of the support force of the jaw on the sliding rod, which is oriented parallel to the longitudinal axis of the connecting rods of this jaw, and the friction force of the jaw on the sliding rod, which is oriented parallel to the axis of the slide T.

[0138] It is also appropriate to define an angle at the apex of a friction cone of adhesion, also called the "angle of adhesion" or "angle of friction".

[0139] The friction cone is formed by the boundary between the space in which the resultant force is such that the sliding rod does not slip relative to the jaw 631, 632 (considering that the two jaws apply symmetrical forces on the sliding rod), and the space in which the resultant force is such that the sliding rod 531 slips relative to the jaw 631, 632. Therefore, the angle of adhesion corresponds to the maximum angle relative to a contact normal of the jaw on the sliding rod 531 in which a force can be applied by the jaw to the sliding rod 531 along the slide axis T without generating a translation of said sliding rod 531.

[0140] And the second means of operation 60 are then configured such that, when the jaws 631, 632 are in proximal position, said resultant angle is less than the friction angle, which locks the sliding rod 531 in fixed position in one direction.

[0141] In other words, the lifting system 1 is configured so that, when the jaws 631, 632 are in their active configuration, the resultant angle is less than the angle at the apex of the friction cone, advantageously less a safety margin. For example, at a coefficient of friction / adhesion of 0.15, the minimum requirement is 9°. The effortless angle is taken to be 8° and will decrease as the load increases.

[0142] It is therefore possible to play on several parameters.

[0143] A first parameter is the force exerted by the actuator 601a on the jaws. However, here, this force is intended to remain limited compared to the other forces in game.

[0144] A second parameter, at least as important as the first, is the angle α ([Fig. 4]) formed, in the proximal position, between the longitudinal axis of any one of the connecting rods and the normal to the jaw (in particular, the normal to its friction face 631a, 632a) on which this connecting rod is articulated. The smaller this angle α is when the jaws 631, 632 are in the proximal position, the more the connecting rods 602, 603, 604, 605 are perpendicular to the friction faces of the jaws.

[0145] The objective is then to adjust this angle a according to the coefficient of adhesion friction between the friction faces 631a, 632a of the jaws and the sliding rod 531.

[0146] Here, since the jaws 631, 632 are made of mild stainless steel (for example, type 316L) and the sliding rod 315 is made of hard stainless steel (for example, type Super-Duplex X2CrNiMoN 25-7-4), the coefficient of friction between these two materials is between 0.15 and 0.2. Therefore, an angle α of 8° allows the sliding rod 531 to be retained when the load C has a weight that is practically zero. As explained above, when the weight of the load C increases, the sliding rod 531 tends to slide in the direction of the decrease in the distance dimension D, which causes the jaws 631, 632 to tighten by friction, so that the rod remains locked despite this increase in load.

[0147] Thus, by geometrically imposing an angle α smaller than that of the natural friction cone between the jaws and the sliding rod under zero load, the load C will remain held when the jaws are closed, regardless of its mass. This is a virtuous system because it is the very presence of the load C that creates its retention. Conversely, this system allows free movement of the sliding rod 531 in the opposite direction when the load C rises. Indeed, in this case, the jaws are pushed open by friction.

[0148] Of course, the materials of the jaws and the sliding rod could be different, in which case the angle a would have to be modified according to the coefficient of adhesion friction between the materials chosen.

[0149] For example, it may be considered that, for a coefficient of adhesion friction between 0.08 and 0.16, the angle may be between 5° and 9°.

[0150] Of course, for a higher value coefficient (for example if the jaws are rubber-coated), angle a may have a higher value.

[0151] Mechanical stops

[0152] When the jaws 631, 632 have been closed in the proximal position and the weight of the load C is high, the sliding rod 531 causes a displacement of the jaws beyond their proximal position (relative to the distal position), by elastic breathing of the parts in compression (connecting rods, jaws, bearing) and in tension (housing).

[0153] The entire system of controlled braking means 6 could be oversized to withstand loads exceeding the recommended maximum, in order to resist unforeseen shocks and stresses. However, this solution would prove to be much less advantageous technically and economically.

[0154] Here, the aim is rather to avoid that if the weight of the load C exceeds a recommended load threshold (for example including dynamic effects such as maximum accelerations imposed on the lifting equipment or shock effects due to the recovery of the lifted load at too high a relative speed (accidental presence of slack), the stresses exerted by the sliding rod 531 on the various components of the controlled braking means 6 (housing, connecting rods and jaws) are too high and cause damage to one of these components.

[0155] For this purpose, as shown in [Fig.3], the controlled braking means 6 include mechanical stops 641, 642 allowing a limit position to be defined for the jaws 631, 632.

[0156] This end-of-stroke position is chosen so that, when the jaws are in this position, the angle a remains strictly greater than 0. Thus, this angle a varies here from a value strictly greater than 8° in the distal position, to a value between 0 and 8° (exclusive limits) in the end-of-stroke position.

[0157] Here, these mechanical stops 641, 642 are adjustable, allowing the end-of-stroke position to be adjusted in situ, and thus the limiting force that can be retained by the jaws. This is a precise, passive force-limiting system with a very high level of repeatability. Upon reaching the end stop, the direction of the resistance forces exerted by the jaws on the sliding rod is significantly affected. Initially imposed by the direction of the connecting rods, the force path being much steeper due to the stops, the slightest increase in force on the sliding rod tends to tilt the resultant force towards the axis of the sliding rod, which very quickly causes it to move out of the friction cone and thus initiates a slippage of the sliding rod under the jaws, which stops naturally as soon as the force returns below the preset threshold. This solution thus acts as a force limiter, like a mechanical safety valve.

[0158] In the embodiment illustrated in [Fig. 3], these are screws, which have the advantage of allowing for recalibration if necessary. It could also be a simple stop of fixed height (calculated in advance).

[0159] As illustrated in this figure, these screws can be screwed into the jaws 631, 632, in order to come into contact with the housing 61 when the jaws reach the end-of-stroke position.

[0160] Alternatively, these screws could be screwed into the housing 61, to form stops against which the jaws would come into contact when the latter arrive in position end of race.

[0161] Other structures could be considered.

[0162] Typically, the stop means could comprise only one screw placed on any one of the jaws, the gears ensuring the symmetrical stop of the other jaw in the end-of-stroke position.

[0163] It is understood that if the weight of the load C is very high, the jaws will bear against these mechanical stops 641, 642, so that the resultant force will fall outside the friction cone. Thus, in this case, the jaws 631, 632 are no longer able to hold the sliding rod 531 in the direction of the reduction of the dimension in distance D.

[0164] Therefore, in the event of a shock causing a sudden and limited increase in the weight of the load C, the load C will be able to descend somewhat, which will prevent all the stresses from being transmitted to the controlled braking means 6 and deforming them plastically.

[0165] Safety ring

[0166] Preferably, safety means are also provided to prevent the jaws 631, 632 from coming into a proximal position in a particular situation:

[0167] - the jaws are in a distal position, and

[0168] - the jaws are controlled to come into a proximal position while the forces applying to the sliding rod 531 tend to a decrease in the dimension in distance D.

[0169] Put another way, the safety means prevent the jaws from coming to rest against the sliding rod 531 when a load C is held by the cable and the load C undergoes a downward movement (for example, when the destination frame Rd on which the load is placed descends relative to the origin frame Ro). Such a technical feature prevents the load C from being suspended mid-wave on the descending front (where the relative velocity is at its maximum, which would generate a potentially destructive dynamic force), and from the load being struck shortly afterwards by the destination frame Rd when the latter ascends on the next wave.

[0170] Preferably, these safety means are designed to automatically interpose themselves between the jaws 631, 632 when the latter are in distal position and the dimension in distance D decreases.

[0171] Here, as shown in [Fig.3], these safety means include a safety ring 65 which encircles the sliding rod 531.

[0172] This safety ring 65 is housed inside the case 61 and is threaded (or fitted) onto the sliding rod 531 so as to be able to slide on it between two distinct extreme positions, called the active position and the inactive position.

[0173] According to the illustrated embodiment, it is located here opposite the means of stop 641, 642 in relation to jaws 631, 632.

[0174] In the active position, the safety ring 65 is intended to come between the jaws in order to prevent the actuator 601a from returning these jaws to the proximal position.

[0175] In the inactive position, the safety ring 65 is located away from the jaws so as not to obstruct their movement.

[0176] The safety ring 65 is mounted on the sliding rod 531 so as to:

[0177] - on the one hand, to be held in a fixed position on the latter when no effort is exerted on this ring, and

[0178] - on the other hand, to be able to slide along the sliding rod 531 when the rod sliding 531 slides and the ring comes to a stop against the housing 61 or against the jaws.

[0179] The safety ring 65 then has a defined oscillating stroke between the housing 61 and the jaws.

[0180] As shown in [Fig.3], the jaws 631, 632 each have a notch on the side of the safety ring 65. These notches together define a cavity 650 open towards the sliding rod 531 and on the opposite side of the sliding ring 65.

[0181] So, the safety ring 65 is designed to be able to fit into this cavity 650 only when the jaws are in distal position and the sliding rod 531 has a movement tending towards a decrease in the dimension in distance D.

[0182] If the jaws are in the proximal position and the rod slides in the same direction (for example because the load C is too high and the jaws are in the end-of-travel position), the safety ring 65 comes to rest against the edges of the jaws so that it cannot come to rest in the cavity 650. It thus remains inoperative.

[0183] If the sliding rod 531 has a movement tending towards an increase in the dimension in distance D, the safety ring 65 comes to rest against a side wall of the case 61. It thus remains inoperative.

[0184] This safety ring 65 is shown in detail in [Fig.5].

[0185] It has substantially cylindrical internal and external faces about an axis of revolution Al, and extends over a height less than the distance separating the jaws and the aforementioned side wall of the housing 61.

[0186] According to a particular embodiment, it advantageously comprises three substantially identical sections 651, each extending over an angular sector of 120°. These three sections 651 are articulated to one another about pivot axes parallel to the axis of revolution AL

[0187] A first of the sections 651 is further secured to a second of these sections via an elastically deformable connection, which allows these two sections to be slightly separated in order to modify the diameter of the safety ring 650.

[0188] In practice, this first section has a hollow cavity 652 in its face external, and a hole opening on one side into this cavity, and on the other to the end of the first section, which faces the corresponding end of the second section. A screw 653 is engaged in this hole such that its head fits into the cavity 652 and its threaded body screws into a tapped bore provided in the second section. A compression spring 654, which is sandwiched between the head of the screw 653 and the edge of the hole, elastically returns the retaining ring to a tighter position where its diameter is minimal.

[0189] Thus, the safety ring 65 can have a variable diameter, between the aforementioned tightened configuration and an enlarged configuration in which its diameter is maximum.

[0190] The inner face of the safety ring 65 has, in the tightened configuration, a diameter strictly less than that of the sliding rod 531, and, in the widened configuration, a diameter strictly greater than that of the sliding rod 531.

[0191] Thus the safety ring 65 remains supported around the sliding rod 531, which allows it to slide with the latter as long as it is not in contact with either the housing 61 or the jaws 631, 632. The stiffness of the compression spring 654 is sufficiently low so that the friction between this ring and the rod remains limited and so that, when the safety ring 65 comes to rest (for example against the housing 61), it does not hinder the sliding of the sliding rod 531.

[0192] In summary, the bistable control executed by the actuator 601a allows the jaws 631, 632 to be placed in three positions, namely:

[0193] - the proximal position, in which the jaws 631, 632 are supported on the neck shank smoothing 531, piloted by the second maneuvering means 60,

[0194] - the distal position, in which the jaws are at a distance from the sliding rod 531, piloted by the second maneuvering means 60, and

[0195] - an intermediate position, in which the jaws 631, 632 are controlled to move to a proximal position from a distal position but the safety ring 65 locks these jaws in an intermediate position between the distal and proximal positions.

[0196] In other words, in the intermediate position, the jaws do not reach the proximal position. The sliding rod 531 is able to slide within the pilot-operated braking means 6.

[0197] In addition, preferably, the safety ring 65 is ejected relative to the jaws 631, 632 in intermediate position when these jaws are piloted from the intermediate position to the distal position.

[0198] In other words, once the jaws are placed on the safety ring:

[0199] - in the direction of the descent of the package (decrease in distance D), the ring of Safety remains between the jaws, drawn in by the sliding of the rod.

[0200] - in the direction of the upward movement of the package (increasing the distance D), the ring of The safety mechanism is naturally ejected from the jaws (aided by a conical shape given to the jaw / safety ring interface) which then fall back onto the sliding rod.

[0201] Means of maneuver

[0202] The first means of maneuver 8 cooperate with said mobile block of sheaves 52.

[0203] These first means of maneuver 8 are configured to restore energy po tentielle on the mobile block of sheave(s) 52 so that: - in inactive configuration, to strive to maintain a constant tension in said at least one lifting cable (thus achieving passive swell compensation), and - in active configuration, strive to increase the distance rating D.

[0204] More specifically, these maneuvering means 8 are configured to accumulate the potential energy from the mobile block of sheaves 52 when the distance rating D decreases.

[0205] In other words, the maneuvering means 8 are intended to restore a restoring force, corresponding to the potential energy restored.

[0206] The maneuvering means 8 are adapted to maintain sufficient tension to tension said at least one lifting cable 3, in inactive configuration and in active configuration of the piloted braking means 6.

[0207] Without being limiting, this tension advantageously depends on the maximum length of said at least one lifting cable 3 which hangs during the passive compensation of the hoe, on the linear density of said at least one lifting cable 3 and on the value of the destabilizing forces (for example winds, accelerations of the reference frames) which tend to make said at least one lifting cable 3 move out of relation to its / their ideal natural position(s) of straightness between the sheaves 51, 52 and the fixed points.

[0208] Preferably, this tension should also be greater than the force exerted by the controlled braking means 6 in the active configuration, in the direction of increasing the distance rating D.

[0209] By “potential energy”, we preferably include: - an elastic potential energy, for example in the form of a spring element (not shown), advantageously mechanical or pneumatic, and / or - gravitational potential energy (also called gravitational potential energy), for example in the form of a counterweight.

[0210] For example, a spring element accumulates elastic potential energy (for example by putting it under stress) when the dimension in distance D decreases.

[0211] Similarly, a counterweight accumulates gravitational potential energy (for example by its vertical displacement) when the distance D decreases.

[0212] In general, the counterweight may possibly be formed by: - the sliding side member 531, and / or - an offset counterweight 85, suspended from one end of the sliding spar 531 (for example at a proximal end, on the winch side 4), directly ([Fig.3]) or via a cable / pulley assembly, and advantageously exerting a tensile force on the sliding spar 531.

[0213] Conversely, the potential energy is here restored in the form of a restoring force, by increasing the distance D.

[0214] Generally speaking, and taking into account the means of operation 8 exerting potential energy on the mobile block of sheaves 52, the dimension in distance D is notably variable depending on the tensile force exerted by the package C via the lifting cable 3: - the distance dimension D tends to increase when the tensile force exerted by the package C decreases, and - the dimension in distance D tends to decrease when the tensile force exerted by the package C increases.

[0215] In other words, the movements of the mobile block of sheaves 52 are determined by: - ​​the tensile force exerted by the package C on the lifting cable 3, - the restoring force corresponding to the potential energy restored by the operating means 8, - the friction forces exerted by the jaws 631, 632, and - and where applicable, the maneuvers in turn and turn exerted on the lifting cable 3 via the winch 4.

[0216] Control methods

[0217] The control means 7 are configured for piloting the winch 4 and possibly pilot-operated braking means 6, particularly during the launching or retrieval operation of package C.

[0218] Such control means 7 include, for example, a computer program implemented by a computer, for example in the form of a programmable logic controller. This computer program advantageously includes instructions which, when the program is executed by a computer, cause the computer to control the winch 4 and / or the controlled braking means 6 (preferably according to an algorithm).

[0219] Preferably, the control means 7 advantageously include a centering module 71 which, in the inactive configuration of the controlled braking means 6, is configured to control the winch 4 so as to position the mobile block of sheaves 52 in a centered position, advantageously an average position centered on an available stroke.

[0220] This centering module 71 advantageously comprises an initial centering module 71a, which aims to position the mobile block of sheaves 52 in a pre-centered position related to an operation to launch package C from a repository.

[0221] The centering module 71 further advantageously includes a slow centering module 71b which is configured so as, in inactive configuration of the controlled braking means 6, to tend to maintain the mobile block of sheaves 52 in a centered position, advantageously an average position centered on an available stroke.

[0222] Preferably, the slow centering module 71b cooperates with means for instantaneous and averaged measurement of the position of the moving block of sheaves 52 over a period of time (period of 30 s to 90 s for example), in particular when the controlled braking means 6 are in inactive configuration.

[0223] The means for instantaneous and averaged measurement of the position of the mobile block of sheaves 52 consist for example of a cable or laser position sensor.

[0224] This slow centering module 71b is configured to drive the winch 4 (in turns and unturns) when the average position of said mobile block of sheaves 52 reaches one or the other of two actuation thresholds along the slide axis T.

[0225] Preferably, the control means 7 advantageously include a safety end-of-travel module 72, which is configured to actuate the winch 4 (in turn and turn) when the mobile block of sheaves 52 reaches one or the other of two end-of-travel thresholds along the slide axis T.

[0226] Preferably, an increasing speed order is imposed by this safety module at the end of travel 72 to avoid the arrival at the end of travel of the mobile block of sheaves 52.

[0227] Preferably, the control means 7 comprise an automatic recovery module 73 and / or an automatic launch module 74, configured to automatically control the winch 4 and the controlled braking means 6 during recovery and / or launch operation of package C, in the manner described below.

[0228] The automatic recovery module 73 and / or the automatic launch module 74 is preferably associated with at least one measuring sensor 75 (for example a laser or a radar, illustrated in [Fig.1]) configured to measure the relative vertical distance between a frame reference 2 and a destination reference, for example in the case where the average distance between the frame reference 2 and the destination reference is not known or is variable.

[0229] Preferably, said at least one measuring sensor 75 allows the relative vertical position of the destination reference frame with respect to the lifting system 1 to be measured, among: - the average position, - the highest position, - the lowest position.

[0230] From these measurements, it is possible to determine: - the instantaneous vertical velocity (by derivation AU / At), - the maximum speed uphill and downhill (over the last 1 to 5 minutes, for example), - the average absolute speed (over the last 5 minutes, for example), - the length to be turned by the winch 4 to obtain the centre of the mobile block of sheaves 52 in the theoretical centred position.

[0231] First embodiment

[0232] As illustrated in [Fig.1], the lifting system 1 consists of a crane having a single lifting point la.

[0233] In this case, the chassis 2 includes a post 2a and an arrow 2b.

[0234] In general, the winch 4, the pulley means 5, the controlled braking means 6 and the maneuvering means 8 are advantageously supported by the chassis 2.

[0235] According to the embodiment illustrated in Figures 1 and 2, the winch 4 and the pulley means 5 are carried by the upright 2a. In particular, the fixed sheave block 51 is articulated at the top of the upright 2a, and the slide means 53 define a translational degree of freedom having a vertical slide axis T, along this upright 2a, so that the movable sheave block(s) 52 extends below the fixed sheave block 51, at a distance from the latter corresponding to the dimension in distance D.

[0236] From then on, the lifting cable 3 extends from the winch 4 to the pulley means 5, then runs horizontally to a pulley carried by the boom to descend back towards the load C.

[0237] The first maneuvering means 8, cooperating with the mobile block of sheaves 52, here use gravitational potential energy. In this mode, they include a counterweight formed partly by the sliding spar 531 and partly by a mass fixed to this sliding spar 531.

[0238] Alternatively, these maneuvering means 8 could include an offset counterweight (not shown), exerting a downward pull on the sliding spar 531.

[0239] Of course, as an alternative, a spring element could have been used.

[0240] As shown in [Fig. 3], in this first embodiment, the pivot axes connecting rods 602, 603, 604, 605 therefore extend horizontally, while the friction faces 631a, 632a of the jaws 631, 632 rise vertically.

[0241] Due to this orientation, it is necessary to compensate for the weight of the jaws 631, 632. This compensation could be achieved actively, by the actuator 601a. ​​However, it is preferably achieved passively, here by a spring 80 which pushes the jaws upwards (the force exerted by the spring counteracting the weight of the two jaws). Alternatively, a counterweight system could be used.

[0242] In this first embodiment, the housing 61 has two opposing openings through which the sliding rod 531 passes. To ensure the smooth sliding of this rod, These openings can be fitted with sliding rings, such as bronze or cupro-aluminum rings.

[0243] Second embodiment

[0244] In a second embodiment illustrated in figures 7 and 8, the slide means 53 define a degree of freedom in translation about the horizontal slide axis T.

[0245] In practice, in this embodiment, the lifting system 1 could consist of a crane, in which case the winch 4 and the pulley system 5 would be carried by the boom. Here, it will be considered to consist rather of a gantry with at least two identical lifting points (only one of which is shown in the figures). In this embodiment, the winch 4 and the pulley system 5 are carried by a horizontal cross member 2b of the gantry.

[0246] In any case, as shown in [Fig.7], the winch 4 (here comprising two counter-rotating motors), the pulley means 5, and the controlled braking means 6 are advantageously supported by the horizontal cross member 2b.

[0247] As illustrated in [Fig.7], the fixed block of sheaves 51 is located at a distance from the winch 4, and the mobile block of sheaves 52 is located between the fixed block of sheaves 51 and the winch 4. Of course, the opposite would be conceivable.

[0248] The controlled braking means 6 are located on the other side of the winch 4 relative to the pulley means 5.

[0249] As shown in [Fig. 8], the sliding rod 531 passes through the fixed block of sheaves 51 so that it can be attached to the movable block of sheaves 52 and pass through the housing 61 of the controlled braking means 6. This sliding rod 531 is supported by support rollers 532, so that it can slide horizontally (as freely as possible, advantageously without friction). Here, one roller is located on one side of the housing 61 (the side opposite the sheaves) and the other roller is located on the other side of the movable block of sheaves 52. These rollers can be formed by rollers mounted on bearings or by any other suitable system.

[0250] Thus, in this second embodiment, the lifting cable 3 extends from the winch 4 to the pulley means 5, then descends back to the load C directly from the fixed block of sheaves 51.

[0251] The maneuvering means 8, cooperating with said mobile block of sheaves 52, again use gravitational potential energy, for example in the form of a counterweight (not shown) offset intended to exert a traction force on the horizontally oriented sliding spar 531, for example via a cable and pulley system.

[0252] In this embodiment, the pivot axes of the connecting rods 602, 603, 604, 605 of the controlled braking means 6 extend vertically, while the friction faces of the jaws extend horizontally. Due to this orientation, it is not no need to compensate for the weight of the bits.

[0253] Lifting method

[0254] At this stage, we can describe in detail the operation of the lifting system 1, with reference in particular to [Fig.6].

[0255] - Passive wave compensation

[0256] We speak of "passive wave compensation" when the lifting system 1 and the package C are based on two different reference frames (the original reference frame Ro and the destination reference frame Rd).

[0257] In this configuration illustrated by vignette VI in [Fig. 6], the control means operate the controlled braking means 6 in the inactive configuration. In practice, the actuator 601a exerts a force Fl on the jaws 631, 632 to move them to the distal position.

[0258] The moving block of sheaves 52 is then subjected to two opposing forces: - the tensile force exerted by package C via lifting cable 3, and - the restoring force corresponding to the potential energy restored by the first means of maneuver 8.

[0259] The resultant F2 of these efforts varies in the following way.

[0260] If the difference in height between the reference frames decreases (for example a wave raises the package C), the tension in the lifting cable 3 decreases and, naturally, the dimension in distance D increases under the action of the first means of operation 8.

[0261] Conversely, if the difference in height between the reference frames increases (for example a wave causes the package C to descend), the tension in the lifting cable 3 increases and, naturally, the dimension in distance D decreases.

[0262] Passively, the lifting cable 3 is advantageously maintained at an average tension (namely preferably a force exerted by the operating means 8 divided by the number of strands of the pulley means 5).

[0263] Preferably, in passive wave compensation, the method includes a winch piloting step 4 to tend to maintain the mobile block of sheaves 52 in an average position.

[0264] This centering of the mobile block of sheaves 52 is ensured here by the aforementioned slow centering module 71b.

[0265] In practice, if an actuation threshold is reached by increasing the dimension in distance D, the slow centering module 71b drives the winch 4 in a turn so as to tend to bring back, advantageously on average, the mobile block of sheaves 52 into a central position.

[0266] Conversely, if an actuation threshold is reached by decreasing the distance dimension D, the slow centering module 71b drives the winch 4 in a way that tends to return, advantageously on average, the moving block of sheaves 52 to a position central.

[0267] Generally, if an end-of-stroke threshold is reached, the end-of-stroke safety module 72 is executed to actuate the winch 4, turning or turning as appropriate, so as to actively push back the mobile block of sheaves 52 relative to said end-of-stroke threshold.

[0268] - Launch

[0269] The present invention further relates to the method of lifting a package C, in particular for lifting a package C in the presence of relative movement due to swell, by implementing a lifting system 1 according to the invention.

[0270] It therefore relates first of all to an operation of launching the package C from the origin reference Ro to the destination reference Rd, in which case the lifting process advantageously comprises several successive steps.

[0271] These steps can be controlled one after the other manually (using a Human-Machine Interface, for example) or, conversely, in a fully automated manner. Alternatively, it would also be possible to provide for semi-automated control, in which some steps would be implemented manually while others would be carried out automatically. Here, this launch operation is performed by the automatic launch module 74.

[0272] Initially, the package is placed on the original reference point Ro and is attached to the lifting cable 3. The operation is then initiated by an operator who presses an ad hoc button connected to the automatic launch module 74.

[0273] The first step consists of ensuring that the jaws are in a distal position and placing, using the winch, the mobile block of sheaves 52 in a mean position centered on an available stroke.

[0274] According to a preferred embodiment, in a second step, the winch 4 is controlled to perform a turning and then turning movement, in order to place the safety ring 65 in the inactive position, against the wall of the housing 61, out of the cavity 650 delimited by the jaws.

[0275] In a third step, the pilot-operated braking means 6 are activated in the active configuration. In practice, the actuator 601a exerts a force Fl on the jaws 631, 632 to bring them into a proximal position and hold them there. At this stage, the safety ring 65 does not prevent the jaws 631, 632 from bearing against the sliding rod 531.

[0276] Then, in a fourth step, the winch 4 is operated in a slew to lift the package C above the destination reference frame Rd (vignette V2 in [Fig. 6]). The force exerted by the jaws on the rod will then be greater the greater the weight exerted by the package C on the lifting cable 3, as illustrated by the resultant force F2.

[0277] Following this step, the lifting system can then possibly be ordered to move the package C to the destination reference Rd.

[0278] In a fifth step, the package C is lowered close to the destination reference frame Rd, preferably so that the package reaches this reference frame when the difference in heights between the reference frames is minimal (for example, close to the highest wave crests of the swell).

[0279] Thus, the winch 4 is controlled in a deflection, for example near a wave crest at the end of a rising front, preferably so that the package C lands on the destination frame Rd and descends at the same speed as the latter (to become tangent to the wave crest). Accompanying a downward movement of the destination frame Rd in this way minimizes the shocks (i.e., the accelerations) experienced by the package C.

[0280] A sixth step is then planned for controlling the pilot-operated braking system 6 in the inactive configuration. In practice, this sixth step can be implemented during, or even before, the fifth step (but after the fourth step). Its implementation is therefore not constrained from a temporal point of view.

[0281] Indeed, this sixth step of switching the controlled braking means 6 to the inactive configuration is not necessarily executed immediately: it is only executed when a condition is met. It is then said to be suspended (or in memory). The suspension condition relates to the force applied by the package C on the sliding rod 531. When this force exceeds a predetermined threshold (related to the presence of a package suspended by the cable that we wish to prevent from falling freely), the step is put on hold. Indeed, as shown in Figure V3 of [Fig. 6], the resultant F2 of the forces applied to the sliding rod 531 cannot be countered by the force Fl exerted by the actuator 601a to open the jaws, so the latter remain closed in the proximal position.This sixth step, however, is executed as soon as the resultant F2 decreases below a threshold (which reflects the fact that the package C is now placed on the destination frame Rd). Indeed, as shown in vignette VI of [Fig.6], the resultant F2 of the forces then applied to the sliding rod 531 can be countered by the force Fl exerted by the actuator 601a to open the jaws, so that the latter open in the distal position.

[0282] Thus, the jaws 631, 632 only open when the weight of the package C has been transferred to the destination reference Rd.

[0283] When said package C thus transfers its weight from the lifting cable 3 to the destination reference frame Rd, said lifting system 1 provides passive compensation for the swell, as described above.

[0284] - Recovery

[0285] The present invention also relates to an operation for recovering the package C in order to bring it back from the destination reference frame Rd to the origin reference frame Ro, in which case the lifting process advantageously comprises several successive steps.

[0286] Here again, these steps can be ordered one after the other manually, or conversely, in a fully automated or semi-automated manner. Here, this recovery operation is ensured by the automatic recovery module 73.

[0287] Initially, the package is placed on the destination reference Rd and is attached to the lifting cable 3. The operation is then initiated by an operator who presses an ad hoc button connected to the automatic retrieval module 73.

[0288] Starting from an inactive configuration as above in which said lifting system 1 provides passive compensation of the swell, the lifting method first includes a step of controlling the piloted braking means 6 to switch them to an active configuration, so that the jaws sandwich the sliding rod 531.

[0289] In practice, as shown in vignette V4 on [Fig.1], the actuator 601a exerts a force Fl on the jaws 631, 632 to bring them towards the proximal position.

[0290] The step of switching the controlled braking means 6 to the active configuration is not necessarily executed immediately: it is only executed when a condition is met. It is then said to be suspended (or "in memory"). The suspending condition relates in this case to the direction of movement of the package C. When the distance dimension D decreases (the package is descending), the step is suspended. The command, however, is executed as soon as the distance dimension D increases. It may therefore happen that it is executed immediately if, at the time the command was given, this dimension was increasing.

[0291] This suspension could be achieved by the control means. However, here, it is advantageously achieved by the safety ring 65 which, when the jaws are in the distal position and the distance dimension D decreases, comes to rest between the jaws 631, 632, in the cavity 650. The jaws cannot therefore be moved to the proximal position since they abut against this safety ring 65. On the other hand, as soon as the distance dimension D increases, the safety ring 65 is ejected, allowing the jaws to reach the proximal position.

[0292] It will be noted that when the safety ring 65 is interposed between the jaws 631, 632, it exerts on the traction rod 531 low intensity friction forces, which do not prevent the latter from sliding in the housing 61 provided that the weight of the package C is not zero.

[0293] In other words, the order is not executed as long as package C is following a downward movement because this would have the possible double consequence, in the worst case, at maximum relative speed, in the middle of the wave:

[0294] - at that moment, to generate a dynamic effect potentially generating damage to the lifting equipment and the package, and

[0295] - on the next wave, to generate a collision of the destination reference frame Rd under the package, if an immediate and high-speed turning action was not taken, potentially damaging to the package (but not damaging to the lifting equipment).

[0296] When the command is executed (vignette V5 in [Fig.6]), the jaws 631, 632 come into contact with the sliding rod 531. As the package C moves upwards, the jaws do not block the sliding rod 531, and the moving block of sheaves 52 continues its movement, increasing the distance D. Once it reaches the crest of the wave, the controlled braking means 6 prevent the distance D from decreasing. The beginning of the descent of the next wave then gradually lowers the package C onto the lifting cable 3. At the end, the package C hangs from the end of the lifting cable 3, above and at a distance from the destination reference frame Rd.

[0297] Then, or even before the wave crest, the winch 4 is controlled in a tack. Preferably, it is controlled in a tack as soon as the jaws 631, 632 reach their proximal position, with constant acceleration up to a predetermined speed setpoint. The movement of the sliding rod 531 will then follow the difference in speed between what the environment imposes (taking up slack) and what the winch 4 will absorb (which will, on the contrary, tend to decrease the distance dimension D).Thus, for example during the "mid-wave" phase where the speeds imposed by the environment are greater than the lifting speed by the winch 4 alone, the sliding rod 531 will continue to take up the slack but, upon reaching the crest of the wave, the rewinding speed of the winch 4 will exceed the speed of raising the package C and therefore the sliding rod 531 will be blocked by the jaws 631, 622 and the package C will therefore gradually transfer its weight onto the lifting cable 3.

[0298] In all cases, the relative velocity of the package C with respect to the original reference frame Ro at the moment of load transfer from the destination reference frame Rd to the lifting cable 3 is strictly zero. This is a major advantage of the lifting system 1 and its control method, since it minimizes the dynamic lifting coefficient (unlike a conventional lifting device, which will inevitably encounter an impact at some point during its operation with a relative velocity much greater than 0 m / s). As the stresses acting on the system are thus reduced, it can be dimensioned accordingly, to the benefit of its weight, size, and cost.

[0299] If a higher wave crest arrives later, package C is likely to be resting on the destination reference frame and rising again under the effect of this wave. In this event, the sliding rod 531 remains free to slide between the jaws, so that package C does not descend and is blocked at a new maximum level.

[0300] Package C is then brought back above the original reference frame Ro, then lowered again using winch 4 back to the original reference frame Ro.

[0301] At this stage, we can make some observations about this recovery operation.

[0302] The first observation is that if the waves are very small, the safety ring 65 might not move into the active position. To avoid this, a slight deflection command could be applied simultaneously with the closing command for the jaws 631, 632. In this case, the relative speed of the package C with respect to the original reference frame Ro at the time of load transfer can reach a maximum of the deflection speed value.

[0303] The second observation is that the lifting system 1, as designed, allows the jaws 631, 632 to be closed in the proximal position at any time during the retrieval operation, due to the presence of the safety ring 65. Of course, to enable the system to continue operations after a fault, it is preferable to start the retrieval operation during a trough. However, if the operation accidentally starts at another time, this will not affect the safety of the operation thanks to the safety ring.

[0304] The third observation is that slack in the lifting cable 3 and "external play" can occur not due to the lifting system 1 itself, but due to the load C. To understand this, we can consider that the lifting system 1 has four lifting points la, and therefore four lifting cables 3 which carry, in pairs, straps for lifting a floating craft. This craft, typically a boat, is then piloted to position itself above the two straps, and these straps are then intended to be raised by the four lifting points. Then, when the jaws 631, 632 close, the cradle formed by the two straps is at zero velocity, and the floating craft must settle into the straps before being lifted. Thus, the cradle will be recovered and will gain speed relative to the floating craft, so that a residual shock will occur at the moment the boat settles into the straps.Minimizing slack and outside play will minimize relative speed and therefore the associated dynamic effects.

[0305] The fourth observation is that the end stops having a force-limiting function, in the event of malfunction or failure to meet specified environmental conditions (or in the event of significant external play), the rod will slide between the jaws, which will limit the dynamic effects induced beyond a certain threshold. From this In this way, none of the components of lifting system 1 will suffer damage.

[0306] The fifth observation is that in the event of a power supply failure: - in compensation for the swell: the lifting system 1 being passive, it continues to function normally; - in lifting: if package C is near a reference point and if this reference point comes back into contact with package C, then the latter rises to the new highest point which will prevent it from hitting this reference point several times.

[0307] The sixth observation is that the lifting system 1 presented, due to its simple and highly mechanized architecture, exhibits a very short reaction time. This reaction time will preferably be less than four-tenths of a second when opening or closing the jaws (i.e., less than one-tenth of the minimum wave period).

[0308] Variant

[0309] Of course, various other modifications can be made to the invention within the scope of the annexed claims.

[0310] Typically, the lifting system 1 could comprise several pairs of jaws housed in the same casing, preferably all controlled by the same actuator. These pairs of jaws could be arranged crosswise around the sliding rod, or superimposed along the sliding rod.

[0311] According to another embodiment, different operating means than those described and illustrated (deformable parallelogram systems) could be considered, but which, when the jaws are in the proximal position, would block the sliding of the rod 531 in only one direction. Typically, the rod and jaws could be fitted with saw-tooth notches that would push the jaws outwards when the rod tends to move in one direction and, conversely, compress the jaws against the rod when the latter tends to move in the opposite direction. According to another embodiment, the jaws could be pushed against the rod by jacks inclined with respect to the axis of the rod.

[0312] According to another embodiment of the invention, the safety means could comprise, instead of the safety ring 65, a sensor for detecting the direction in which the sliding rod moves and for controlling the jaws accordingly. However, the solution illustrated in the figures is more robust than a solution based on such a sensor.

Claims

Demands

1. A lifting system (1) for a package (C), preferably between two reference frames (Ro, Rd) exhibiting at least one relative vertical motion, for example for lifting the package (C) in the presence of relative motion due to swell, which lifting system (1) comprises at least one lifting point (la) which includes a frame (2) comprising: - at least one lifting cable (3) associated with: — a winch (4), for maneuvering said lifting cable (3), in turns and unwinding, — means of pulley systems (5) comprising: — a fixed block of sheaves (51), secured to said frame (2), and — a movable block of sheaves (52), cooperating with said frame (2) by means of sliding means (53) defining a degree of freedom in translation orthogonally to axes of rotation (51', 52') of said blocks of sheaves, the dimension in distance (D) of said movable block of sheaves (52) with respect to said fixed block of sheaves (51) being variable, - controlled braking means (6), cooperating with said mobile block of sheaves (52) and controllable between two preferably bistable configurations: — an inactive configuration, in which said controlled braking means (6) allow free translation of said moving block of sheaves (52) according to said translational degree of freedom, particularly adapted to passive wave compensation, and — an active configuration, in which said controlled braking means (6) allow the moving block of sheaves (52) to move in a single direction according to said translational degree of freedom, corresponding to an increase in said dimension in distance (D), - control means (7), for piloting said winch (4) and said piloted braking means (6), particularly during launching or retrieval operations for said package (C), - of the first means of maneuver (8) which cooperate with said mobile block of sheaves (52) and which are configured to restore potential energy to said mobile block of sheaves (52) so as: — when said controlled braking means (6) are in inactive configuration, to tend to maintain a constant tension in said at least one lifting cable (3) and, — when said controlled braking means (6) are in configuration active, tending to increase said dimension in distance (D), characterized in that said sliding means (53) comprise a sliding rod (531) which carries the movable block of sheaves (52), which is guided in translation coaxially with said degree of freedom in translation and which cooperates with said controlled braking means (6), and in that said controlled braking means (6) comprise: - at least two jaws (631, 632) which are distributed around said sliding rod (531), which jaws (631, 632) each have a friction face (631a, 632a) adapted to cooperate with said sliding rod (531), - second bistable means of operation (60) adapted to move each jaw (631, 632) between two positions: — a distal position, at a distance from said sliding rod (531), corresponding to said inactive configuration of said controlled braking means (6), and — a proximal position, supported on said sliding rod (531), corresponding to said active configuration of the controlled braking means (6).

2. Lifting system (1) of a package (C) according to claim 1, characterized in that the friction faces (631a, 632a) of the jaws (631, 632) extend parallel to said translational degree of freedom, and in that said second operating means (60) guide the movement of each jaw (631, 632) along an arc-shaped trajectory in which said friction face (631a, 632a) moves parallel to itself, between said two distal and proximal positions.

3. Lifting system (1) of a package (C) according to claim 2, characterized in that the second operating means (60) comprise an actuator (601a) and, for each jaw (631, 632), a deformable parallelogram structure comprising: - said jaw (631, 632), - a base (61), and - at least two connecting rods (602, 603, 604, 605) each assembled in free rotation with said base (61) and with said jaw (631, 632) about two distinct pivot axes, which deformable parallelogram structure cooperates with said actuator (601a) for the operation of said jaw (631, 632) between its distal position and its proximal position.

4. Lifting system (1) of a package (C), according to claim 3, characterized in that at least two connecting rods (602, 603, 604, 605), belonging to two separate deformable parallelogram structures, cooperate together by means of gears (602a, 603a, 604a, 605a), so as to ensure the synchronization of the associated jaws (631, 632).

5. Lifting system (1) of a package (C) according to any one of claims 3 or 4, characterized in that, in proximal position, the angle between the plane passing through the pivot axes of each connecting rod and the normal to the friction face (631a, 632a) is between 5° and 9° if the coefficient of adhesion friction between each friction face (631a, 632a) and said sliding rod (531) is between 0.08 and 0.

16.

6. A lifting system (1) for a package (C) according to any one of claims 1 to 5, characterized in that, at the level of each jaw (631, 632), said lifting system (1) has the following parameters: - a resultant angle, corresponding to an angle formed by the resultant of the forces applied between said jaw (631, 632) and said sliding rod (531), - an angle at the apex of an adhesion friction cone, corresponding to the maximum angle with respect to a contact normal oriented perpendicularly to said sliding rod (531) in which a force can be applied to the sliding rod (531) according to said translational degree of freedom without generating translation of said sliding rod (531), and in that said lifting system (1) is configured such that, when the jaws (631, 632) are in active configuration, said resultant angle is less than said angle at the apex of the adhesion friction cone.

7. Lifting system (1) of a package (C) according to any one of claims 1 to 6, characterized in that the piloted braking means (6) comprise mechanical stops (641, 642) to define an end-of-stroke position for the jaws (631, 632) which is located beyond said proximal position and which is such that, in the end-of-stroke position, all components of the piloted braking means (6) are deformed elastically only.

8. A lifting system (1) for a package (C), according to any one of claims 1 to 7, characterized in that the sliding means (53) are configured such that said sliding rod (531), and its degree of freedom in translation, are oriented horizontally or vertically, and in that, when said degree of freedom in translation is oriented vertically, the piloted braking means (6) include means for compensating the weight of the jaws (631, 632).

9. Lifting system (1) of a package (C), according to any one of claims 1 to 8, characterized in that the piloted braking means (6) include safety means which are configured to prevent piloting from the inactive configuration to the active configuration during a translation of the sliding rod (531) corresponding to a decrease in said dimension in distance (D).

10. Lifting system (1) of a package (C) according to claim 9, characterized in that the safety means comprise a safety ring (65) which encircles said sliding rod (531) so as to move between two positions: - an active position, during a translation of the sliding rod (531) corresponding to a decrease in said dimension in distance (D), to cooperate with the jaws (631, 632) in inactive configuration and prevent piloting from the inactive configuration to the active configuration, and - an inactive position, during a translation of the sliding rod (531) corresponding to an increase in said dimension in distance (D), to move away from the jaws (631, 632) in inactive configuration and to allow piloting of said jaws (631, 632) from said inactive configuration to said active configuration.

11. Lifting system (1) of a package (C), according to any one of claims 1 to 10, characterized in that it consists of: - a crane having a lifting point, the chassis of which has an upright and a boom, or - a gantry having at least two lifting points.

12. A method for lifting a package (C), between two reference frames (Ro, Rd) preferably having at least one relative vertical movement, for example for lifting the package (C) in the presence of relative movement due to swell, by implementing a lifting system (1) according to any one of claims 1 to 11, which lifting method comprises: - for moving the jaws (631, 632) from the proximal to the distal position: — the control of the second operating means (60) for moving the jaws (631, 632) from the proximal to the distal position, Then, — if a force exerted on the sliding rod (531), coaxially with said degree of freedom in translation in a direction corresponding to a decrease in said dimension in distance (D), is less than a predetermined threshold, execution of said command, otherwise — suspension of said order until said effort decreases below said predetermined threshold, then execution of said order, - for the transition from the distal to the proximal position of the jaws (631,632): — the command of the second means of operation (60) to move the jaws (631, 632) from the distal position to the proximal position, then, — if said dimension in distance (D) increases, execution of said command, otherwise — suspension of said order until said distance rating (D) increases.

13. A lifting method according to claim 12, characterized in that it comprises the following operations: (i) during a launching operation of said package (C) from the reference frame (Ro) of the lifting system (1) to a destination reference frame (Rd): - a step of suspending said package (C) from said lifting cable (3), in which the jaws (631, 632) are in distal position and said mobile block of sheaves (52) is in a mid-position centered on an available stroke, - optionally, in combination with claim 10, a turning and drifting step over a stroke allowing the safety ring (65) to be positioned in the inactive position, - a closing command step for the jaws (631, 632) towards the proximal position, - a turning step to lift the package (C) and place it above the destination repository (Rd), - a stage of lowering said package (C) near the highest wave crests of the swell, - when the package (C) is placed on a wave crest or near a wave crest at the end of a rising front, a step of deflection, preferably to come tangent to said wave crest, and of passage from the proximal position to the distal position of the jaws (631, 632), so that when said package (C) transfers its weight from said lifting cable (3) towards said destination reference frame (Rd), said lifting system (1) provides passive wave compensation, and / or (ii) during a retrieval operation of said package (C) located on the destination datum (Rd), with the jaws (631, 632) in the distal position, said lifting system (1) providing passive wave compensation, - preferably when said package (C) is in an upward movement, a step of passing the jaws (631, 632) into a proximal position so that said mobile block of sheaves (52) continues its movement increasing said dimension in distance (D), this up to a wave crest where said mobile block of sheaves (52) is blocked in translation, - as soon as the jaws (631, 632) reach the proximal position, a turning step to lift the package (C) and place it above the reference point (Ro) of the lifting system (1), - a step of lowering said package (C) onto the reference point (Ro) of the lifting system (1).

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